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Great balls of fire

OBSERVATIONS with the Hubble Space Telescope are adding weight to the idea
that gamma-ray bursters are fireballs expanding at nearly the speed of light in
distant galaxies. The bursts of gamma rays have puzzled astronomers for more
than two decades(“God’s firecrackers”, New Scientist, 31 May, p 28).

Earlier this year, ground-based telescopes spotted a new optical source at
the place in the sky where a gamma-ray burster had appeared in February. Hubble
imaged the visible source on 26 March and again on 5 September, when the object
had faded to just two-thousandths of its earlier brightness.

At a meeting on gamma-ray bursters in Huntsville, Alabama, Andrew Fruchter of
the Space Telescope Science Institute in Baltimore said the pictures show the
burst was a dramatic explosion on the fringes of a galaxy billions of light
years away. “These observations are consistent with colliding neutron stars
creating the fireball,” he says.